Twelve worshippers were shot dead at a church in southeast Nigeria on Sunday, with authorities suggesting the bloodshed was due to a local feud.

At around 6:00 am (0500 GMT) at least one gunman opened fire at St. Philip’s church in Ozubulu, near the city of Onitsha, unleashing terror on the congregation. Chukwuma Emeka said he had just stepped out of the church to stretch his legs “when I heard gunshots and screaming and people running inside.”

“When the chaos subsided I went inside, I saw my fellow church members dead in a pool of their own blood and many others were screaming in pain.”

Attacks on churches are rare in southern Nigeria, where there is a predominantly Christian population. The country’s mainly-Muslim north has been gripped by a violent campaign by Boko Haram jihadists, who specialise in targeting religious centres.

There were varying accounts of what happened in Ozubulu. Witnesses said five gunmen in masks stormed the church, but police said the killing was the work of a lone shooter. “So far, 12 persons have been confirmed dead and deposited in the mortuary here,” a worker at Nnamdi Azikwe University Teaching Hospital told AFP.

Several worshippers with gunshot wounds were also receiving treatment at the hospital, the source said. Witnesses said they feared that up to 20 people may have died. Garba Umar, Anambra State police Commissioner, said the attacker was a gunman who “went on a shooting spree, killing and wounding” worshippers.

He said the violence was the result of a failed murder attempt, tied to a feud within the local community. “The information at the disposal of the police is that the gunman had been hired to kill a particular family person believed to be among the worshippers,” he said. Local rights activist Emeka Umeagbalasi said his information about the motive largely concurred with that of the police version.